Currently, when two cells have the same write timestamp
and both are alive or expiring, we compare their value first,
before checking if either of them is expiring
and if both are expiring, comparing their expiration time
and ttl value to determine which of them will expire
later or was written later.
This was based on an early version of Cassandra.
However, the Cassandra implementation rightfully changed in
e225c88a65 ([CASSANDRA-14592](https://issues.apache.org/jira/browse/CASSANDRA-14592)),
where the cell expiration is considered before the cell value.
To summarize, the motivation for this change is three fold:
1. Cassandra compatibility
2. Prevent an edge case where a null value is returned by select query when an expired cell has a larger value than a cell with later expiration.
3. A generalization of the above: value-based reconciliation may cause select query to return a mixture of upserts, if multiple upserts use the same timeastamp but have different expiration times. If the cell value is considered before expiration, the select result may contain cells from different inserts, while reconciling based the expiration times will choose cells consistently from either upserts, as all cells in the respective upsert will carry the same expiration time.
\Fixes scylladb/scylladb#14182
Also, this series:
- updates dml documentation
- updates internal documentation
- updates and adds unit tests and cql pytest reproducing #14182
\Closes scylladb/scylladb#14183
* github.com:scylladb/scylladb:
docs: dml: add update ordering section
cql-pytest: test_using_timestamp: add tests for rewrites using same timestamp
mutation_partition: compare_row_marker_for_merge: consider ttl in case expiry is the same
atomic_cell: compare_atomic_cell_for_merge: update and add documentation
compare_atomic_cell_for_merge: compare value last for live cells
mutation_test: test_cell_ordering: improve debuggability
(cherry picked from commit 87b4606cd6)
Closes#14649
The tombstone_gc was documented as experimental in version 5.0.
It is no longer experimental in version 5.2.
This commit updates the information about the option.
Closes#13469
(cherry picked from commit a68b976c91)
Our handling of NULLs in expressions is different from Cassandra's,
and more uniform. For example, the filter "WHERE x = NULL" is an
error in Cassandra, but supported in Scylla. Let's explain how and why.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Closes#12494
This PR is V2 of the[ PR created by @psarna.](https://github.com/scylladb/scylladb/pull/11560).
I have:
- copied the content.
- applied the suggestions left by @nyh.
- made minor improvements, such as replacing "Scylla" with "ScyllaDB", fixing punctuation, and fixing the RST syntax.
Fixes https://github.com/scylladb/scylladb/issues/11378Closes#11984
* github.com:scylladb/scylladb:
doc: label user-defined functions as Experimental
doc: restore the note for the Count function (removed by mistatke)
doc: document user defined functions (UDFs)
List the queries that support the TIMEOUT parameter.
Mention the newly added support for TRUNCATE
USING TIMEOUT.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Fix https://github.com/scylladb/scylladb/issues/11373
- Updated the information on the "Counting all rows in a table is slow" page.
- Added COUNT to the list of selectors of the SELECT statement (somehow it was missing).
- Added the note to the description of the COUNT() function with a link to the KB page for troubleshooting if necessary. This will allow the users to easily find the KB page.
Closes#11417
* github.com:scylladb/scylladb:
doc: add a comment to remove the note in version 5.1
doc: update the information on the Countng all rows page and add the recommendation to upgrade ScyllaDB
doc: add a note to the description of COUNT with a reference to the KB article
doc: add COUNT to the list of acceptable selectors of the SELECT statement
Fix https://github.com/scylladb/scylla-doc-issues/issues/816
Fix https://github.com/scylladb/scylla-docs/issues/1613
This PR fixes the CQL version in the Interfaces page, so that it is the same as in other places across the docs and in sync with the version reported by the ScyllaDB (see https://github.com/scylladb/scylla-doc-issues/issues/816#issuecomment-1173878487).
To make sure the same CQL version is used across the docs, we should use the `|cql-version| `variable rather than hardcode the version number on several pages.
The variable is specified in the conf.py file:
```
rst_prolog = """
.. |cql-version| replace:: 3.3.1
"""
```
Closes#11320
* github.com:scylladb/scylladb:
doc: add the Cassandra version on which the tools are based
doc: fix the version number
doc: update the Enterprise version where the ME format was introduced
doc: add the ME format to the Cassandar Compatibility page
doc: replace Scylla with ScyllaDB
doc: rewrite the Interfaces table to the new format to include more information about CQL support
doc: remove the CQL version from pages other than Cassandra compatibility
doc: fix the CQL version in the Interfaces table
It was recently decided that the database should be referred to as
"ScyllaDB", not "Scylla". This patch changes existing references
in docs/cql/cql-extensions.md.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
It was pointed out to me that our description of the synchronous_updates
materialized-view option does not make it clear enough what is the
default setting, or why a user might want to use this option.
This patch changes the description to (I hope) better address these
issues.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
